A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright right whatsoever.
This invention relates generally to battery-back up systems for supplying alternating current (xe2x80x9cACxe2x80x9d) or direct current (xe2x80x9cDCxe2x80x9d) power to electrical loads. More particularly, this invention relates to methods and apparatus for collecting information on the status of one or more back-up batteries and communicating the information to the users of uninterruptable power supply (xe2x80x9cUPSxe2x80x9d) systems.
There are numerous types of UPS systems for supplying backup AC or DC power to a load with batteries or other energy storage devices. The back up power is required when power from an AC power source is performing outside of acceptable limits or fails completely. UPS systems that supply AC power to an AC load, as a back-up to an AC power source, are referred to herein as AC to AC (xe2x80x9cACxe2x80x94ACxe2x80x9d) class UPS systems. Those that supply DC power to a DC load, as a back up to an AC power source, are referred to as AC to DC (xe2x80x9cAC-DCxe2x80x9d) class UPS systems.
Prior art battery back-up systems have used one very high voltage battery pack made up of a number of series connected 12 volt automobile batteries, for example. This battery pack is not very reliable for a power back-up system because the whole battery pack is lost if one of the batteries fails and creates an open circuit. It is known to use parallel coupled battery packs to avoid the foregoing problem but even when one of these battery packs fail it is time consuming to identify the particular one or two or more battery packs that require replacement.
Furthermore, in prior art battery pack back-up systems it has been complicated to collect and process battery pack voltage and charge and discharge currents for evaluating the individual battery packs whether connected in series or parallel.
The present invention overcomes the limitations of prior art battery back-up systems by coupling a digital data processor to one or more batteries or battery packs. The processor is used to gather information about the status of an individual battery pack and report the information to a user by setting off an alarm. The battery pack information is also made available for viewing on an LCD display. In addition, a communication system is created among at least a single battery pack and a main processor associated with the power control circuit of a UPS system.
Accordingly, it is an object of the present invention to employ digital processors with a battery to gather information about the battery including whether it is over heating, needs replacement, is capable of being charged, is at float voltage and whether it is a good battery capable of supplying full power to a load.
Another object of the invention is to identify a battery in a group of batteries that requires replacement by coupling a light emitting or an audio alarm to each battery in the group.
Still another object of the invention is to communicate battery information collected at a battery to a remotely located digital processor such as the processor used in the power control circuit of a UPS system.
It is another object to integrate battery pack information into the computer system administrating a UPS system having battery packs for power back-up.
Yet another object of this invention is to enhance the performance of battery packs in UPS systems used with computer, telephone, process control and other down time sensitive electrical loads where loss of power means loss of information or service.
Additionally, it is an object to enable a UPS system processor to communicate with a monitor associated with each battery in a group of one or more batteries which are providing back-up power to an electrical load.
Finally, it is an object of the invention to detect a battery pack among a group of battery packs electrically coupled together that requires service and to notify users in advance of trouble so there is time to service the battery pack, for example, by replacing it with another battery pack.
The foregoing and other objects of this invention are realized by the presently disclosed embodiment of a UPS system. The disclosed UPS system is for an ACxe2x80x94AC class system. It is adaptable for use in an AC-DC class UPS system and with a stand alone group of back-up batteries or battery packs. The UPS system uses a power control circuit of the type having a multi-tap transformer to pass power from an AC power utility source to an electrical load. An AC line sensor is coupled to the AC source load to monitor for over and under voltage conditions in addition to total loss of the line source. A UPS processor is coupled to the line sensor and the transformer to electrically select particular taps on the primary winding to compensate for under and over voltage conditions. A triac power switch is also coupled to the line source and the UPS processor. The processor de-energizes the triac when it detects that the AC line is about to fail to disconnect the UPS system from the line. When the AC source comes back on the line sensor senses the event and signals the processor to switch the triac to reconnect the AC source to the transformer.
The power control circuit includes a MOSFET bridge that is coupled to a tertiary winding of the transformer and to the plus and minus voltage buses connecting a group of 48 volt battery packs coupled together in parallel. The UPS processor supplies 30 khz (approximately) signals to the gates of the MOSFETs in the bridge to convert the 48 volts DC supplied by the battery packs to about 48 volts 60 hz AC. The bridge also functions to convert the 48 volt AC power developed in the tertiary winding by the AC line source to 48 volt DC for charging the battery packs.
Battery monitors are packaged inside the housing of each battery pack. Processors on the monitors receive battery pack voltage and charging and discharging current information. A shunt resistor which is part of the monitor is coupled in series with each battery pack. The voltage and current information along with ambient temperature information are processed by the monitor processor and an information packet is transmitted to the UPS processor. Telephone handset lead line and male and female handset RJ-22 connectors are used to couple the UPS processor to the monitors associated with each of the battery packs.
The UPS processor issues commands to the monitors which regenerate the commands and send them along to the other monitor. Simultaneously with the receipt of the UPS command, the monitors send battery pack information back to the UPS processor. Commands are transmitted to the monitors until the UPS processor detects that it is no longer receiving information back. The UPS processor gathers the information and provides it to an LCD display upon user request entered with a three key keypad or upon the request of a system administrator from a supervisor computer over a local area network or other communication resource.